Preheat the grill or grill pan to medium-high heat (400–450°F). Generously oil the grill to prevent sticking and ensure even cooking.

Prepare the peaches by halving them and removing the pits. Lightly brush the sides and skins with oil. Grill the peaches for about 4–5 minutes, flipping halfway until they're tender and beautifully charred. Chop the grilled peaches and set them aside in a medium bowl.

Mix the salsa by adding diced red pepper, jalapeño, red onion, lime juice, cilantro, chili powder, salt, and pepper to the bowl with the chopped peaches. Gently toss the mixture and taste it for seasoning, adjusting as desired. Refrigerate until ready to serve.

Combine the glaze in a large bowl, mixing peach preserves, olive oil, soy sauce, mustard, garlic, and jalapeño. Season with salt and pepper. Set aside 1/3 cup of this glaze for later use.

Prepare the chicken by halving the breasts horizontally and pounding them to an even thickness. Drizzle olive oil, salt, and pepper on both sides. Grill the chicken for 8–10 minutes, flipping once, and brushing with the peach glaze (not the reserved 1/3 cup), until it reaches an internal temperature of 160–165°F.

Rest the chicken by tenting it with foil and letting it stand for 5–10 minutes. Brush the reserved 1/3 cup of peach glaze over the cooked chicken and generously top it with the fresh peach salsa.

Optional: Serve with a side of rice for a complete meal.